juliepoudrier Posted January 20, 2009 Report Share Posted January 20, 2009 This subject may be more appropriate for the livestock section, but I thought it was an interesting story, especially when we get into discussions about border collies and what they were meant to be and how they are changing--and that some folks think the changes are inevitable and necessary and that trying to save those "old things" is pointless. This is a story about Jacob sheep that was published in the American Livestock Breeds Conservancy newsletter. I am paraphrasing it here. The story starts in 1999 when a couple who raise Jacob sheep took two lambs to Texas A&M because they believed that the lambs had a rare congenital defect known as occipital condylar dysplasia. It turns out the lambs did not have that genetic defect but instead had a lysosomal storage diseae. There are various types of lysosomal storage disease, and animals or humans with the disease lack an enzyme that breaks down waste products from the spinal cord-brain connection. The ultimate result is loss of coordination, appetite, and sight, and eventually death. The university and the breeders traced the genetic problem back to one suspected sire, but to confirm he was the "culprit" the breeders had to continue breeding carriers to prove him as the source. So for four more years the couple continued to breed both suspected carriers and noncarriers. The hope was also to be able to identify the nature of the lysosomal storage disease these sheep carried. The couple made the findings known to other Jacob breeders, and continued breeding and kept a small group of suspected carriers in the hope that the disease might be fully identified, although since the Jacob sheep isn't commercially important, research was not a high priority. They kept that small group of carriers basically on faith. Fast forward to 2008 when researchers at Texas A&M contacted the breeders to tell them that the disease in their Jacob sheep was the same form of the disease that occurs in children: Tay-Sachs. They wanted to know if the breeders still had carriers in their flock, which they did, and those carriers were confirned with DNA and new enzyme tests. To make a long story short, a Tay-Sachs gene therapy consortium was established in 2007. This is a group of researchers in the US and UK who hope to start a gene therapy clinical trial for Tay-Sachs disease within the next four years. Tay-Sachs is incurable, as are many diseases that are related. Like Tay- Sachs, some of them are fatal. According the the article, "the genetic similarities between sheep and man and other neurological diseases are as close a match as we may ever get." "Another member of the Consortium, Dr. Miquel Sena-Esteves of the Massachusetts General Hospital and Harvard Medical School remarked: 'The goal of identifying and eliminating Tay-Sachs in Jacob sheep in order to preserve the breed is a noble goal. But we who are working on a human gene therapy cure are very happy that you did not succeed and kept the carriers for the last decade. These sheep are genetically significant." So in this case, conserving a rare breed and the efforts of one couple to find out what was causing health problems in their lambs might lead to a cure for a fatal human disease. If you're someone who is interested in breed conservation, like me, and someone asks you "Why bother?" well here's a story that gives you a reason why. J. Quote Link to comment Share on other sites More sharing options...
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